removed yggdrasil.js

there is an npm yggdrasil instead
server set to use socket.io front_end

index.html is now testing front-end page
stream_log event added

CLIENT: socket.emit('stream_log', {server_name: 'a', file_path:
'/var/games/minecraft/servers/a/logs/latest.log'})
cleaned up tail code

renamed to start_tail and tail_data events